1. Field of the Invention
The present invention relates to an optical apparatus, such as a camera, having a cartridge chamber in which a film cartridge is to be loaded.
2. Description of Related Art
Recently, a film cartridge having a new form different from the forms of conventional film cartridges has been proposed. In the film cartridge having the new form, a film leading end is not led out of the cartridge unlike the conventional film cartridges. When the cartridge is loaded in a camera or the like, a film is first reeled out of the cartridge and is then advanced to a film take-up spool with thrust driving.
The film in the new cartridge is given with a tendency to curl, i.e., core-set curl, which causes the film to wind around a spool in the cartridge. When the film is moved along a film transport path with the thrust driving, the film is forced to round in the widthwise direction into an arcuate shape due to the core-set curl, and a force for transporting the film from the cartridge with the thrust driving is imparted to the whole of film extending out of the cartridge so that the pliable film can reach the film take-up spool.
In this connection, if a film outlet 1h of a film cartridge 1 is set to locate in the same direction as a film transporting direction that is perpendicular to the optical axis of a photographing lens, as shown in FIG. 20, the film extending out of the cartridge with the thrust driving cannot maintain the arcuate shape of a radius R due to the presence of a pressure plate, etc., and a buckled portion 18a occurs in the arcuate film.
Additionally, in FIG. 20, reference numeral 1i denotes a door for opening and closing the film outlet lh of the film cartridge 1. When the door 1i is closed, the film outlet 1h is perfectly shielded against light. Reference numeral 18 denotes a film which has been thrust (pushed) out of the film cartridge 1.
If the buckled portion 18a occurs in the arcuate film in such a manner, the thrust force is no longer imparted to the leading end of the film 18. If the thrust driving is further continued in such a condition, the film 18 is bent at the buckled portion 18a, thus resulting in that it becomes impossible to not only thrust the film, but also rewind the film because the leading end of the film is folded one part over another part.
Therefore, the film outlet 1h of the film cartridge 1 is generally set to orient rearward about four degrees with respect to the film transporting direction 18b (see FIG. 22) that is perpendicular to the optical axis of the photographing lens, so that, as shown in FIG. 21, the film can always maintain the arcuate shape of the radius R during the thrust driving.
As seen from FIG. 22 which shows a cross-section of a camera, if the film outlet 1h of the film cartridge 1 is set to orient rearward an angle E, for example, about four degrees, with respect to the film transporting direction 18b that is perpendicular to the optical axis of the photographing lens, for ensuring the film extended out of the cartridge to take an optimum arcuate shape during the thrust driving, a problem arises in that a part of the film cartridge, including the film outlet 1h, protrudes in the back-and-forth direction of the camera, and a thickness of the camera increases correspondingly.
One conceivable method to suppress such an increase in thickness of the camera, i.e., to minimize a thickness F of the camera in the direction of an optical axis 14a of a photographing lens 14, is to form an outer casing cover 8 of metal and construct a part of a cartridge chamber 9, which is formed of plastic, by the outer casing cover 8, as shown in FIG. 22.
With the above method, however, because the cartridge chamber 9 has a limit in its wall thickness for ensuring positive shield against light, edges 9b, 9c and 9d of the plastic-made cartridge chamber 9, which are positioned at the boundaries with respect to the outer casing cover 8, cannot be formed into very sharp edges, so that steps are produced between the edges 9b, 9c, 9d and the outer casing cover 8.
As seen from FIG. 23 which shows a bottom surface of the camera, a cartridge insertion opening formed at the bottom of a camera body, therefore, also has steps between the edges 9b, 9c, 9d and the outer casing cover 8.
Because of the steps between the edges 9b, 9c, 9d and the outer casing cover 8, gaps are left between an inner periphery of the cartridge insertion opening and an outer periphery 13a of a packing 13, which is provided around a cartridge chamber lid 2 to be fitted to the cartridge insertion opening, when the cartridge chamber lid 2 is closed. Accordingly, the cartridge chamber 9 cannot be sufficiently shielded against light.